Improvement in automatic telegraphs



UNITED STATEs PATENT Eric.

CHARLES WHEATS'IONE AND JOHN MATTHIAS AUGUSTUS STROH, OF

LONDON, ENGLAND..

IMPROVEMENT IN AUTOMATIC TELEGRAPHS.

Specification forming part of Letters Patent No. 166,168, dated July 27,1875; application filed March 16, 1875.

To all whom 'it may concern:

Be it known that we, Sir CHARLES WHEAT- SCLONE, of 19 Park Crescent,Regents Park, knight, and J oEN MATTHIAS AUGUSTUS STROH, of 29 TolmersSquare, Hampstead Road, mechanician, both of London, county ofMiddlesex, England, have invented certain Improvements in theTransmitters of Automatic or Fast-Speed Telegraphs, of which thefollowing is a specification:

The present invention is an improvement on the transmitter of SirCharles Wheatstones automatiotelegraph system, which transmitter, asformerly constructed, was the subject of a patentgranted to him in theUnited States on the 22d of December, 1874.

The present improvement consistsin the introduction ofa secondcommntating arrangement, by which, after the ordinary current (whichdetermines either a dash or a space) has been transmitted, a weakercurrent in the same direction is sent after it. Certain irregularitiesof transmission which occur under the usual arrangements are in thismanner obviated.

A front elevation of the improved transmitter is shown in theaccompanying drawing.

The perforated paper strip is drawn with a uniform velocity between theluted roller C and the circular depression in the horizontal ledge B bythe spur-Wheel M, the teeth of which enter into the central line ofholes and hold it in position. The motion is effected by means of aspring or weight connected with a train of wheels. llhe vertical Wiresor pins p p', which enter, respectively, into the upper and lowerline-oi` perforations of the paper strip,` are connected with thebell-crank levers I and J, and are forced upward by the spiral springs sand s'. rlhese levers are placed on opposite sides of the rocking beamL, and are alternately depressed by the arms l and c, which protrudefrom it at equal distances from its center. When a hole occurs in thepaper strip, through which either of the vertical pins isfree to enter,the lever attached to it follows the beam upward, remaining in contactwith the arm of the beam on that side and the circuit remains unbroken;but if no hole occurs inthe paper strip, the vertical pin rising againstit is stopped, `and the bell-crank lever is prevented following the beamupward. The protruding` arm of the beam, therefore, separates from thelever, and the circuit is interrupted. When either ofthe vertical wiresor pins rises up through a hole in the paper it engages with one of thegrooves of the luted roller C, which carries it forward until theopposite oscillation of the beam causes it to be withdrawn. The twobell-crank levers I and J are connected together electrically throughthe brass sides of the frame.V The brass spiral springs s and s' tend topress.

those levers into contact with the pins l and c of the rocking beam. Thearm Z is in metallic connection with the line-terminal. The rockingbeam, on its right-hand side, is furnished with a third projectingcontact-arm, e, in metallic connection with the earth, vand which, withthe arm c on the same side ofthe center, makes (when the beamoscillates) alternate contact with the opposite faces of the twocontactlevers G and H. The lever H is in permanent connection, throughthe slab F, with the copper pole. The lever G is in permanentconnection,through the slab E, with the zinc pole of the battery. Whenthe righthand side of the beam is elevated the contact-arm e pressesagainst the face of G and puts the zinc pole to earth. At the same timethe arm c is pressed against H, which forms the metallic prolongation ofthe copper pole. If an aperture occur in the paper strip at this momentthe ends of I andJ are in contact with c and Z, and the copper currentpasses from H, through c, I, the springs s and s', J, to l and line. If,on the other hand, no aperture occurs in the paper strip, the end of Iis prevented following the beam, and the linecircuit is interrupted onthat side by the separation of the contact c. When the beam is in theopposite position a similar action takes place, with the difference that`the other pole of the battery is then put to earth through e, and thatthe interruption of the line-circuit takes place between l and J in theevent of no aperture occurring in the paper strip.

The arrangement for sending a weak current into the line at the end of adash or space is effected by the insertion of an artilicial resistanceinto the battery and line circuit. This is done by means of thecontactlever K, centered upon a-slab, K', between E and F, and which isin connection with the line-terminal through a resistance-coil. Thecontact-lever K is moved from side to side, against screw-points upon Eand F, by the rods I and J, coupled, respectively, to the ends of thebell-crank levers I and J. The ends of these rods pass through suitableholes in the opposite sides of the lever K, but they are supplied withebonite adj usting-nuts, so that whenever either of the vertical pinsenters alternately into an aperture in the paper strip one end of itslever follows the rocking beam L, while the other thrusts the lever Kfar enough to carry it over the center of the friction-wheel d, whichholds it in place until its position is changed to the other side. Whenthe contact-tongue K rests against the screw-point of E a zinc currentpasses from E through K, and through the resistance into .the line,whenever the beam is depressed on that side, which puts the lever H andarm e in con tact, and therefore copper to earth. The opposite takesplace when the tongue rests against the screw-point of F, acoppercurrent passing from F through K and the resistance R into the linewhenever the rocking beam is in the other direction, which puts zinc toearth, and these currents can therefore only occur when the rocking beamreturns to the same position it was in when the lever K was thrust over.Whenever a full current is sent into the line through the levers I and Jand arms c and l, a parallel current is also sent through the duplicatecircuit formed by the resistance and contact tongue, and whenever thebeam returns to this position, while no aperture occurs in the paper,the lever remains unmoved, and a current in the same direction will besent into the line through the resistance only. In this Way, as the lastposition of the beam during a dash or space is the same as the p0-sition which determined the dash or space, although no aperture occursjust then in the paper strip, a weak current is sent in the samedirection through the resistance and into the line, because during theformation of the dash or space the lever K has not been thrust from itsfirst position. By thus causing a strong instantaneous current to befollowed by a weaker one, in order to produce a dash or long space, adot immediately following a long space, or a short space following adash, is prevented from becoming unduly elongated, as without suchcompensation this defect occasionall y happens.

Having thus described our said invention, we would have it understoodthat what We claim is- The means for sending a weak current into theline at the end of a dash or space, for preventing an undue elongationof short currents, consisting of the lever K, operated from thetransmittinglevers, the contact-points F E, and the resistance andbranch circuit, substantially as set forth.

G. WHEATSTONE. A. STROH.

Witnesses:

FREDK. HARRIS, B. J. B. MILLS,

0f 23 Southampton Buildings, London.

